The present invention generally relates to color video signal recording and/or reproducing systems, and more particularly to a color video signal recording and/or reproducing system which does not introduce degradation in the reproduced picture even in a recording system in which the horizontal synchronizing signal recorded positions are substantially not formed in alignment in a direction perpendicular to the longitudinal direction of a linear recording track, or in a radial direction of a spiral or concentric recording track, and especially suitable when applied to a magnetic recording and/or reproducing apparatus, a video disc, and the like.
Generally, in the recording system of a SECAM system color video signal recording and/or reproducing apparatus, for example, a SECAM system color video signal is supplied to a low-pass filter and a band-pass filter, and a luminance signal is separated and filtered by the low-pass filter while a carrier chrominance signal is separated and filtered by the band-pass filter. The above carrier chrominance signal is a signal in which a first frequency modulated signal obtained by frequency modulating a first color sub-carrier frequency by a color difference signal B-Y, and a second frequency modulated signal obtained by frequency modulating a second color sub-carrier frequency by a color difference signal R-Y, are formed into a signal every one horizontal scanning period (1H), in an alternate, time-series, and composite manner. The above carrier chrominance signal having a carrier frequency of 3.9 MHz to 4.75 MHz, for example, is supplied to a frequency dividing circuit wherein the carrier chrominance signal is frequency-divided and converted into a frequency in a lower frequency range. Moreover, the carrier frequency of the carrier chrominance signal is set to within a range between 0.97 MHz to 1.19 MHz, for example, and the frequency deviation width is reduced. The carrier chrominance signal converted into the lower frequency range thus obtained, and the chrominance signal which has undergone frequency conversion, are separately multiplexed and amplified into a composite color video signal, and then supplied to a pair of magnetic heads having mutually different azimuth angles.
On the other hand, in the reproducing system, the above pair of magnetic heads alternately reproduce the composite color video signal recorded on the magnetic recording medium (magnetic tape). The outputs of the pair of magnetic heads are respectively amplified, and are formed into a continuous signal by being alternately changed over a switching circuit. The frequency modulated luminance signal in the above continuous signal obtained, is separated and filtered by a high-pass filter, and then demodulated and converted into a luminance signal by a demodulating circuit. The carrier chrominance signal in the low frequency band in the above continuous signal, is separated and filtered by a low-pass filter, and then supplied to a band-pass filter to be returned into a predetermined frequency band, after being returned to the original carrier frequency by a multiplying circuit. These reproduced carrier chrominance signal and the reproduced luminance signal supplied from the above demodulating circuit, are formed into a reproduced SECAM system color video signal by a composite circuit, in a composite manner.
In the above described recording and/or reproducing apparatus, one tape pattern fromed on the magnetic tape, for example, is one in which mutually adjacent tracks are formed without guard bands, by use of a pair of magnetic heads having mutually different azimuth angles. In this type of a tape pattern, for example, the horizontal synchronizing signal recording positions are arranged and aligned in a direction perpendicular to the longitudinal direction of the track. The alignment of the horizontal synchronizing signal is referred to as an H-alignment. Furthermore, the frequency modulated signal component of the carrier chrominance signal recorded after being converted into a lower frequency region, is the same at a certain recorded interval where the carrier chrominance signal is recorded, and at the position on an adjacent track from the above certain recorded interval, where the color difference signal R-Y is frequency modulated. Accordingly, very little cross-talk is introduced between adjacent tracks due to the carrier chrominance signal in the lower frequency range, and the demodulated color video signal is hardly affected by the above cross-talk.
However, a case will now be considered in which only the tape travelling speed is reduced to one-half that upon normal operation without varying the diameter of the drum, the tape width, the rotational speed of the drum, and the number of horizontal scanning lines of the reproducing apparatus, to perform a long-duration recording or reproduction in the magnetic recording and/or reproducing apparatus which forms the above described tape patterns, that is, to perform four hours of recording or reproduction, for example, by use of a magnetic tape for performing a two-hour recording or reproduction. In the tape pattern obtained in this case, the horizontal synchronizing signal recorded positions are not aligned in the adjacent tracks, that is, the horizontal synchronizing signal recording positions are not in an H-alignment. Accordingly, no correlation exist between the adjacent tracks, and the carrier frequency of the carrier chrominance signal in the low frequency range differ in the adjacent tracks. Moreover, since the adjacent tracks are recorded by use of the pair of magnetic heads having mutually different azimuth angles, the azimuth loss in the frequency modulated luminance signal in the high frequency range becomes large, and little cross-talk is introduced between the adjacent tracks. However, since the recorded carrier chrominance signal is in the low frequency range, the azimuth loss becomes small, and furthermore, because the carrier frequencies of the carrier chrominance signals aligned and recorded in the adjacent tracks differ, the demodulated color signal is greatly affected by the cross-talk introduced from the adjacent tracks. Moreover, beat interferences are also introduced.